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compareFloat.cpp

//////////////////////////////////////////////////////////////////////////////
//
// Copyright (c) 2004, Industrial Light & Magic, a division of Lucasfilm
// Entertainment Company Ltd.  Portions contributed and copyright held by
// others as indicated.  All rights reserved.
//
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//
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//       copyright notice, this list of conditions and the following
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//
//     * Redistributions in binary form must reproduce the above
//       copyright notice, this list of conditions and the following
//       disclaimer in the documentation and/or other materials provided with
//       the distribution.
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//     * Neither the name of Industrial Light & Magic nor the names of
//       any other contributors to this software may be used to endorse or
//       promote products derived from this software without specific prior
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//////////////////////////////////////////////////////////////////////////////

#include <compareFloat.h>

using namespace Imf;


bool
equivalent (float f1, float f2, Compression comp)
{
    //
    // Test if a float, f1, is "equivalent" to another float, f2,
    // which results from storing f1 in an image file, and reading
    // it back:
    // If the file was compressed with PXR24_COMPRESSION, then f1
    // and f2 must the same as f1 rounded to 24 bits (see class
    // ImfPxr24Compressor); otherwise f1 and f2 must be the same.
    //

    union
    {
      float       f;
      unsigned int      i;
    } u1, u2;

    u1.f = f1;
    u2.f = f2;

    if (comp == PXR24_COMPRESSION)
      return (u2.i >> 8) - (u1.i >> 8) < 2;
    else
      return u2.i == u1.i;
}

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